1. Field of the Invention
The present invention relates to a sheet conveying method for tearing off a staple of a center binding stapler and a sheet post-processing apparatus including conveying means for the sheet conveying method.
2. Description of the Related Art
As it is well known, in recent years, an image forming apparatus having plural functions is spread. A sheet post-processing apparatus including a stapler for stapling sheet ends, a sheet post-processing apparatus including a saddle unit having sheet processing functions such as sheet center folding and sheet center biding, or the like is connected to such an image forming apparatus.
US 2004/0254054A1 discloses a sheet post-processing apparatus having sheet post-processing functions for applying punching (a punch unit), sheet end binding (a stapler), center binding (a center binding stapler), center folding (a center folding blade and a center folding roller), and the like to a plurality of sheets conveyed from an image forming apparatus. Center binding stapling and center folding methods and a mechanism for the methods in a center binding and bookbinding mode of the sheet post-processing apparatus are disclosed. There is also a sheet post-processing apparatus including a stapler for stacking a plurality of sheets conveyed from an image forming apparatus, putting the sheets on standby, and aligning the sheets and center-binding a bundle of the aligned sheets along a center line.
Conventionally, such a center binding stapler capable of performing center binding includes a hammer and an anvil. In such a stapler, after stapling a bundle of sheets, when sheet conveyance is started while a staple used for the stapling cuts into and remains in the anvil, the sheet conveyance is not normally performed and a sheet jam occurs.
In such a case, in order to prevent a sheet jam, there is a technique for forcibly tearing off a staple for stapling cutting into an anvil using a solenoid or the like.
However, in such a case, a solenoid or the like exclusively used for tearing off the staple for stapling is necessary and cost is high. Further, a space for providing the solenoid or the like is necessary.
Therefore, it is an object of the present invention to provide a sheet conveying method that can efficiently and easily tear off a staple for stapling from an anvil and a sheet post-processing apparatus including conveying means for the sheet conveying method.